Generally, a vacuum assisted closure (VAC) therapy or a negative pressure wound therapy (NPWT), being classified as a kind of adjuvant physical therapy, is operated by applying a negative pressure pump to a patch of a bio-compatible porous wound dressing covering a wound for forming a negative pressure inside the wound, by that, as the negative pressure will cause the volume of the porous wound dressing to contract and consequently force the wound to close as well as the shear stresses of the contracted porous wound dressing will cause a drag to the boundary tissues of the wound for enhancing cell division and proliferation, the healing of the wound can be accelerated. It is noted that the application of the negative pressure through the porous wound dressing not only can improve the growth of blood vessels and the local blood circulation as the flowing of tissue fluid between cells can be enhanced, but also it can prevent the happening of edema and inflammation, create a moist healing environment with good wound protection as it can draw cellular waste and excess tissue fluid out of the wound, and thus the healing time of the wound can be reduced.
Conventionally, the development of a NPWT system must go through several clinical experiments just to verify its effectiveness in physical and biological therapy. Currently, it is common to use living animal, such as pig, rabbit or mouse, in such clinical experiments. However, not to mention the difficulties in development of a NPWT system using the result of such animal experiment as there are conceivable differences between human tissue and animal tissue, just the more and more strict animal experiment regulation by the effort of humanitarian and animal protection associations will cause huge delay in developing a mature NPWT product.
In view of the aforesaid shortcomings, there are already many phantoms that are capable of mimicking human tissue being developed for using in those therapeutic effectiveness verifications, such as solid water phantom, polystyrene phantom acrylic phantom, thermoplastic phantom and gelatin phantom, etc. The aforesaid phantoms are mostly being molded into blocks or other geometrical shapes so as to facilitate the proceeding the effectiveness verifications. It is noted that the gelatin phantom made of animal protein can be applied in applications more than those other phantoms. In food industry, it can be made into all kinds of soft sweets, mousse, jelly, meat aspic, cakes, and so on; and in pharmaceutical industry, it can be made into hard capsules, soft capsules, sugar-coated pills, and so on; and in biomedicine industry, it can be made into artificial dressings, artificial skins and phantoms, and so on. As the gelatin can form a smooth and elastic jelly that its strength is adjustable according to its gelatin concentration, and is a hydrophile jelly capable of melting into liquid-like glue when it is heated to a temperature above 40° C. and solidifying back into jelly when it is cooled down to below 30° C., phantoms of different elasticity and thicknesses can be made from gelatins of different compositions for the purpose of mimicking different layers in a human skin like epidermis layer, dermis layer, and subcutaneous layer. Moreover, the gelatin phantom can be formed with a plurality of layers, each having channels formed therein to be used for operating as the blood vessels in the skin as there can be a blood mimicking fluid flowing in those channels.
However, as the channels of different layers in the conventional gelatin phantom are not formed interconnecting with each other, the blood mimicking fluid is prohibited from flowing between layers so that even the blood mimicking fluid flowing in the channels of the topmost layer is flowing under a sculpted wound formed on the gelatin phantom and can not ooze out of the wound just likes an actual skin wound does. It is known that the human blood and tissue fluid are capable of flowing between skin layers and thus it is for sure that there will be blood and tissue fluid ooze out of an open wound at any time during the healing. Therefore, the conventional gelatin phantom can not mimic the exudate of an open wound, there will be errors when it is used for experimenting how exudates can affect the efficiency of a negative pressure wound therapy (NPWT) system.